Include file cleanup : dce.h

[Rémi Assailly]

Alexandre Julliard wrote :

>The easy stuff has been done already...
>
Otherwise there would be nothing to do !

I noticed that in gdi.h PC_SYS_MAPPED is unused and PC_SYS_RESERVED is 
only used in dlls/x11drv/palette.c
I think we can remove PC_SYS_MAPPED and move PC_SYS_RESERVED to 
dlls/x11drv/palette.c

In other cases, what do you suggest ?

If it is too difficult and if I can only be a cleaner, I'll be a cleaner ;)